One of the most striking differences in the smoking patterns between African American (AA) and White smokers is the preference for mentholated cigarettes by African Americans. While approximately 80% of African American smokers smoke mentholated cigarettes, the proportion among White smokers is only about 20%. Although Bupropion has been shown to be effective for smoking cessation among smokers in general, preliminary research suggests that Bupropion may be less effective among African American smokers of mentholated cigarettes. One possible mechanism for lower efficacy of Bupropion among menthol smokers is that menthol may affect the pharmacokinetic profile of Bupropion. This is a 2-year exploratory study designed to provide information needed about interaction between menthol in mentholated cigarettes and Bupropion (Zyban(r), Glaxo SmithKline). We will evaluate the effects of menthol in mentholated cigarettes on the pharmacokinetic profiles of Bupropion and its 3 principal metabolites, hydroxybupropion, threohydrobupropion, and erythrohydrobupropion. Twenty African Americans who smoke mentholated cigarettes will be matched 1:1 with 20 African Americans who smoke non-mentholated cigarettes. Matching will be by age, gender, cigarettes per day smoked (CPD), and body mass index (BMI). After a 1-week placebo run-in period, all subjects will take 300 rag/day of sustained-release Bupropion for 20 days. Pharmacokinetic (PK) parameters of Bupropion and its 3 principal metabolites will be assessed at steady state under 2 conditions- Smoking and Non-smoking. These PK parameters will be compared between 1) menthol and non-menthol smokers, and 2) Smoking and Non-smoking Conditions. Because AA smokers predominantly smoke mentholated cigarettes, showing significant interactions between menthol in cigarettes and Bupropion could have profound clinical (choice of treatment) and public health (policy changes) implications for the pharmacotherapy of smoking cessation.